AT_SYMLINK_NOFOLLOW acts on the symlink itself rather than following it.
AT_EMPTY_PATH acts on the directory if path is empty.
Currently, this is implemented in fstatat itself but the code is general
enough to be refactored once we get the other *at functions. It could
likely just live in openat itself.
Closes: #212
The fix is simply to not follow links when opening a file to be renamed.
O_NOFOLLOW, a non-POSIX extension, does exactly that while not needing
renameat or openat.
Linux's variant uses the syscall as intended. Redox's variant uses fpath
to build a path to pass to fstat from the file descriptor plus the file
name. Unlike the syscall, this isn't atomic so the liminal space between
fpath/getcwd and fstat is subject to TOCTOU.
Beyond fstatat, I moved the stat test to its correct location and added
an assert since the output of the test is unchecked.
I also added AT_FDCWD which seems to be -100 across Unixes. The other
AT_* constants are unimplemented for now.
The implementation for confstr is straightforward. Most of the constants
return 1 on both musl and glibc. The only constant that doesn't is
required for Fish.
I also switched an #[unsafe(no_mangle)] from my last patch back
to a #[no_mangle] because we need to bump cbindgen. #[unsafe(no_mangle)]
is required for Rust 2024.
Most platforms use a c_int though glibc uses a u32. GNU defines a type,
__rlimit_resource_t, for the RLIMIT enum that is a u32.
Using a c_int is nicer for a few reasons. The first is that our
(unimplemented) functions receive a c_int for the enum - using a u32 is
technically wrong but doesn't affect anything since the constants are
turned into macros by cbindgen.
The second reason is that a c_int is nicer for libc and nix (the crate)
too since we don't need to pollute the crates with guards for Redox.
%m is a format specifier that prints an error string for errno. The
specifier is technically only for syslog, but musl and glibc implement
it for printf itself. Parsing for a single specifier in a single
function is error prone, especially when syslog itself is variadic.
* Fix PERROR to match musl/glibc better
* More unit tests + enabled on Linux
* Pack priority and facility into one i32 and check the bits with
bitflags
* Add LOG_UPTO (logic is straight from musl)
Not done:
* "%m" - this could just be added to printf
* LOG_CONS
Linux's syslog is a local socket, so this uses the recent UDS work.
* Most of redox.rs is refactored into mod.rs now which has all of the C
facing functions and consts.
* I wrapped the global logger in a Mutex instead of a RwLock. The logger
is almost always locked for writing so a Mutex is simpler as RwLock
provides no benefits.
* I implemented LOG_PERROR which also prints errors to stderr as well as
the log.
* Syslog should be sys/syslog.h with syslog.h as an alias (the
original code only had syslog.h).
This test should rename disabled until redox-os/relibc#212 is fixed. The
test works on Linux so it should work on Redox eventually too.
The issue is non-trivial because it involves a syscall, frename, that
may need to be redesigned. frename requires a file descriptor, but
opening a file resolves links which in turn fails with broken symlinks.
Wildan Mubarok